Chapter 1 (In conjunction with 11)

Question 1

What is kVp and how does it affect the beam?

Answer 1

Kilovoltage peak

Controls the strength or penetration - QUALITY of the beam

Question 2

What is mAs and how does it affect the beam?

Answer 2

Miliamperage seconds

Controls the number of xrays (photons) - QUANTITY

Question 3

What is the relationship between kVp and contrast?

Answer 3

Inverse

The higher number of kVp, the lower the contrast

Question 4

What is the minimum percent of change needed in kVp to visualize it with the human eye?

Answer 4

10%

Question 5

What controls the photon wavelength?

Answer 5

kVp

Question 6

What is the relationship between wavelength and photons?

Answer 6

Inverse relationship -

Shorter the wavelength, the stronger the photon

Longer the wavelength, weaker the photon

Question 7

What is the 15% rule?

Answer 7

In order to maintain optimum exposure while increasing kVp # by 15%, you must decrease the mAs by half.

Decreasing kVp by 15%, increase mAs by double

Question 8

What happens if image is under-penetrated or over-penetrated?

Answer 8

Under-penetration:
Not enough kVp to penetrate through the body
Looks milky white, no bony trabecular pattern

Over-penetration:
Too much kVp
Darker image

Question 9

What is the relationship between mAs and photons?

Answer 9

Direct relationship

As the mAs # increases, so does the amount of photons

Question 10

What is the relationship between kVp and the power of a photon

Answer 10

Direct relationship

As kVp increases, the power of the photon increases making it easier to penetrate through a body part

Question 11

What is the minimum percent change in mAs to visualize it with the human eye?

Answer 11

30%

Question 12

How are wavelength and frequency related?

Answer 12

The longer the wavelength, the lower the frequency